1. Field of the Invention
The present invention relates to an electronic apparatus that can operate in a power saving mode, a control method therefor, and a storage medium storing control program therefor.
2. Description of the Related Art
In a recent electronic apparatus like an image forming apparatus, the number of functions increases and the functions are made highly functional, which tends to increase the maximum electric power consumption. Since electric power that can be supplied through one power supply line is limited, the method of supplying insufficient electric power temporarily from a battery that is connected in parallel to the power supply is proposed (for example, see Japanese Laid-Open Patent Publication (Kokai) No. 2007-5944 (JP 2007-5944A)).
On the other hand, such an image forming apparatus is provided with power saving operational modes in addition to a normal mode. When the apparatus does not perform operations, such as printing, the apparatus make a transition to a power saving operational mode and operates with low power consumption. For example, the apparatus goes into one power saving operational mode in the intervals between printings. The apparatus frequently goes into this power saving operational mode and frequently returns to a normal operational mode. Moreover, the apparatus goes into another power saving operational mode on a weekend etc. In this power saving operational mode, the apparatus operates under ultra-low power consumption state for long time.
An electronic apparatus using a battery needs to avoid overdischarge and overcharge of the battery. However, when the apparatus is used in a power saving operational mode, the apparatus keeps an overcharge state in long time or is left in an overdischarge state unless charge and discharge are controlled appropriately.